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5 Classes of Chemical Agents

The classification of chemical agents depends on the purpose of the organization or professionals involved. For example, scientists group chemical agents into seven categories to precisely identify the effects they induce, with an additional six classifications based on the chemicals' origin. To help chemical disaster response, many government organizations identify four types of chemical agents, based on their effects. The North Atlantic Treaty Organization, or NATO, uses five classes of chemical agents to include vomiting gases, according to the Nebraska Public Health Laboratory.

Choking Agents
- Choking or pulmonary agents impede the lungs' capacity to function normally, and restrict breathing, with symptoms that include tightness of the chest, coughing and choking. Colorless or greenish-yellow in color, these agents give off an odor that smells like bleach or fresh hay. Choking agents such as chlorine and phosgene are liquids dispersed in gas form and can induce severe lung damage in four hours, leading to death, reports the federal Disaster Information Management Research Center, or DIMRC.
Blood Agents
- Blood agents are highly volatile and act rapidly to restrict red blood cells during respiration. A victim's skin, eyes and lips will turn red, and he will gasp for air upon exposure. Colorless gas that smells like bitter almonds, examples include hydrogen cyanide and cyanogen chloride. The DIMRC explains that blood agents will induce seizures, cause respiratory failure and lead to cardiac arrest shortly after exposure.
Blister Agents
- Blister agents such as sulfur and nitrogen leave second- and third-degree burns on the body -- internally and externally. They appear as a clear or a brownish oily liquid, depending on purity, and give off an odor that smells like mustard or garlic. Symptoms will include burning eyes, severe lung damage, a raspy cough and blisters on the skin. While mortality rates are low with blister agents, death can occur due to lung complications.
Nerve Agents
- Nerve agents inhibit the body from controlling muscle contractions, with effects occurring within 10 minutes of initial exposure. Some nerve agents, such as sarin, tabun and samon, can cause death within 15 minutes. Others, such as VX, cause death within 42 hours. Common symptoms include twitching, convulsions, salivation and pupils that look like pinpoints. Nerve agents have a fruity or sweet odor and will vaporize.
Vomiting Agents
- One well-known vomiting agent is adamsite. Victims usually inhale the chemical agent with initial symptoms of nasal, respiratory and ocular irritation. Vomiting, nausea and diarrhea usually occur thereafter and the poisoning can last for several hours. Vomiting agents don't usually result in fatalities, but serve as harassing or incapacitating agents. While many government organizations don't include this classification, NATO does.

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